Grand Rounds


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Grand Rounds

  1. 1. Grand Rounds
  2. 2. NATURE AND MANAGEMENT OF COMITANT CONVERGENT STRABISMUS <ul><li>Before dealing with specific types of strabismus, there are general factors that must be considered when assessing the suitability for treatment, which apply to all cases regardless of the condition. </li></ul>
  3. 3. Evaluation <ul><li>Age </li></ul><ul><li>Age at onset </li></ul><ul><li>Type of strabismus </li></ul><ul><li>Angle of strabismus </li></ul><ul><li>Depth of sensory adaptations </li></ul><ul><li>Cooperation of patient and parent </li></ul>
  4. 4. Age <ul><li>under 4 years – no co-operation for exercises: Rx and occlusion possible only </li></ul><ul><li>Over 8-9 years – not possible to restore BSV: cosmetic treatment only </li></ul><ul><li>Most adults have come to terms with the strabismus and require refraction only. Some may want cosmetic surgery. </li></ul>
  5. 5. Age at Onset <ul><li>this is critical (may have to refer to old photos) </li></ul><ul><li>especially important to establish if the onset was within the first year (Px is more likely to have eccentric fixation, DVD, latent nystagmus) </li></ul><ul><li>Next establish if onset is within the first 3 years </li></ul><ul><li>Significance? : the younger the Px is at onset and the longer time to presentation, the worse the prognosis. </li></ul><ul><li>NB May never have developed binocularly driven cells and therefore cannot expect to obtain BV </li></ul><ul><li>If very recent onset the Px is more likely to have distressing symptoms and may require immediate referral (esp. if incomitant) </li></ul>
  6. 6. Type of Strabismus : <ul><li>some Pxs respond better to refractive/orthoptic treatment than others </li></ul><ul><li>different methods of treatment are more appropriate for different types. </li></ul>
  7. 7. Angle of Strabismus <ul><li>the greater the angle the worse the prognosis </li></ul><ul><li>>20∆ - surgery indicated </li></ul><ul><li>15-20∆ - other factors must be favourable for orthoptics </li></ul><ul><li><15∆ - good for orthoptics </li></ul><ul><li><6∆ - microtropia, no orthoptics necessary </li></ul>
  8. 8. Depth of Sensory Adaptations <ul><li>the deeper, the worse the prognosis </li></ul>
  9. 9. Cooperation of Patient and Parent <ul><li>must have high levels of interest and perseverance and reasonable intelligence. </li></ul><ul><li>Parents must give time for supervision of exercises </li></ul>
  10. 10. Refractive Esotropias <ul><li>Fully accommodative esotropia </li></ul><ul><li>Partially accommodative esotropia </li></ul><ul><li>Convergence excess </li></ul>
  11. 11. Fully Accommodative Esotropia <ul><li>Deviation is secondary to the presence of hyperopia </li></ul><ul><li>Excessive accommodation for distance and near stimulates excessive convergence sufficient to cause a strabismus </li></ul><ul><li>Onset usually 2-5 years; coincident with the increased use of accommodative effort </li></ul><ul><li>AC/A ratio is usually normal </li></ul><ul><li>BSV present in nearly all cases; may have microtropia if anisohyperopic </li></ul><ul><li>Usually no or only slight amblyopia, unless strabismus is present for a long time </li></ul>
  12. 12. Management <ul><li>Correction of refractive error </li></ul><ul><li>full cycloplegic Rx for constant wear </li></ul><ul><li>Review 3-4 weeks later </li></ul><ul><li>Check that no more latent hyperopia has become manifest and alter Rx is big difference </li></ul><ul><li>Check state of BV and microtropia if aniso. </li></ul><ul><li>Treat any suppression still present (simultaneous vision cards on the Holmes stereoscope; bar reading; appreciation of physiological diplopia) </li></ul>
  13. 13. Management <ul><li>If amblyopia worse than 6/12, may require period of direct part-time occlusion if under 7 years. NB if microtropia present, VA will never be equal </li></ul><ul><li>NB Often a refractive error is all that is necessary </li></ul><ul><li>Carefully selected Pxs may be able to remove Rx for sports or social events etc and can be helped to gain BSV without Rx by orthoptics </li></ul>
  14. 14. Criteria: <ul><li>hyperopia < 4.00DS </li></ul><ul><li>Astigmatism < 1.00DC </li></ul><ul><li>Cooperation – Px should be of reading age (7 ish) </li></ul><ul><li>Motivation – older children are best as they are more self-conscious regarding specs </li></ul><ul><li>Parent’s cooperation is also essential. Warn that the Px will still need Rx at least for closework </li></ul>
  15. 15. Method <ul><li>(i) teach Px recognition of pathological diplopia (eg coloured filters & spotlight, with or without vertical prism or CT to reveal other image) or train to stop accommodating (make the image go blurred) For many control of esotropia will occur spontaneously after (i). </li></ul>
  16. 16. Method <ul><li>If not: (ii) Obtain BSV at intersection of visual axis and extend this area. Exercise fusional ranges (esp negative). Practice at home. </li></ul><ul><li>(iii) Improvement of binocular VA without Rx by increasing negative relative convergence (difficult) eg bar reading whilst gradually reducing the Rx and print size; -ve lenses whist watching TV (take care to maintain BSV and not suppression); stereoscope; miotics for 3-4 weeks (HES; dual action) </li></ul><ul><li>NB Most hospital departments want to see all fully accommodative strabismics. Any treatment should be taken cautiously and preferably in liaison with the HES. </li></ul>
  17. 17. Partially Accommodative Esotropia <ul><li>Constant deviation but increases with accommodative effort </li></ul><ul><li>Associated with hyperopia but residual angle still present with when corrected </li></ul><ul><li>Usually amblyopia </li></ul><ul><li>Onset 1-3 years; insidious </li></ul><ul><li>BSV depends on the age of onset; usually not present </li></ul><ul><li>Associated vertical deviation common (IO overaction of one or both eyes) </li></ul>
  18. 18. Management <ul><li>depends on the size of the residual angle. </li></ul><ul><li>Referral is likely in most cases </li></ul><ul><li>Full cycloplegic result given </li></ul><ul><li>Treat any amblyopia by occlusion </li></ul><ul><li>Re-inforcement and extension of BV – if it can be found to exist where the visual axes cross </li></ul><ul><li>Introduce objects closer than and further than object of fixation to try to get Px to appreciate physiological diplopia – gradually move object in towards fixation object to overcome suppression, maintaining physiological diplopia </li></ul>
  19. 19. Management <ul><li>bar reading at fixation distance where axes cross </li></ul><ul><li>if above obtained easily , try to move point of fixation to reduce angle of deviation </li></ul><ul><li>Refer for surgeons opinion:- for functional result if BSV demonstrated; otherwise cosmetic </li></ul>
  20. 20. Convergence Excess <ul><li>High AC/A ratio (>6:1) </li></ul><ul><li>Strabismus at near only OR angle much greater at near </li></ul><ul><li>Strabismus may only be present when looking at fine detail </li></ul><ul><li>Onset 2-5 years, occasionally earlier </li></ul><ul><li>Most have BSV, some microtropia </li></ul><ul><li>Amblyopia rare (except in anisometropia) </li></ul><ul><li>Most hyperopic but some are emmetropic or even myopic. </li></ul><ul><li>It is important to differentiate convergence excess from non-accommodative near SOT (has normal AC/A ratio) and undercorrected hyperopia ( eg do cycloplegic). </li></ul>
  21. 21. Management <ul><li>Depends on the AC/A ratio </li></ul><ul><li>If >8-10∆/D, unlikely to respond conservatively </li></ul><ul><li>Also if near deviation is >25 - 30∆, refer for surgery </li></ul>
  22. 22. Management <ul><li>Otherwise: </li></ul><ul><ul><li>correction of refractive error – full cycloplegic Rx, unless Px is myopic then give a slight undercorrection </li></ul></ul><ul><ul><li>amblyopia treatment (if necessary) by PT occlusion </li></ul></ul><ul><ul><li>Bifocal spectacles – find an add that eliminates near deviation (by CT) enabling PX to maintain comfortable BSV with adequate binocular VA for all near activities </li></ul></ul><ul><ul><li>Start with +1.00 Add and increase in 0.50 steps </li></ul></ul><ul><ul><li>Try Fresnels on one month trial </li></ul></ul><ul><ul><li>Give large flat top seg set high bisecting pupil </li></ul></ul><ul><ul><li>Carefully fit and give full instructions </li></ul></ul><ul><ul><li>Gradually reduce add in time and discard if possible </li></ul></ul><ul><ul><li>Use a bar reader to establish BSV </li></ul></ul><ul><ul><li>Problem: dependency on add by young adults, poor fitting and compliance by children and wear and tear </li></ul></ul>
  23. 23. Management <ul><li>Contact Lenses – Calcutt (1984) reported that CLs (sometimes with extra +1.00D) reduced the angle by up to 15∆, often producing a latent deviation and useful BSV. Needs further trials </li></ul><ul><li>Miotic drugs – combined with orthoptics (particularly good for 2-5 year olds whose cooperation is poor for other methods. Use over a period of weeks) </li></ul><ul><li>Orthoptics for use without the Rx – minority of Pxs > 6 years; good cooperation and small deviations </li></ul><ul><li>Antisuppression treatment </li></ul>
  24. 24. Management <ul><li>Control of deviation by extending area of BSV – move target closer </li></ul><ul><li>Increase binocular VA – increase –ve fusional reserves (usually needs some optical correction to achieve) </li></ul><ul><li>Of minimal value on its own but can be useful in conjunction with other treatment or surgery </li></ul><ul><li>Surgery – especially where the prognosis is poor for orthoptics or other methods have failed </li></ul>
  25. 25. Non-refractive Esotropias
  26. 26. Constant: <ul><li>Onset 1-2 years </li></ul><ul><li>Strabismic amblyopia common </li></ul><ul><li>Often have an associated vertical deviation </li></ul>
  27. 27. Intermittent:
  28. 28. Near esotropia <ul><li>Ortho or small SOP on distance fixation </li></ul><ul><li>Moderate/large SOT for near </li></ul><ul><li>No amblyopia </li></ul><ul><li>Often no significant refractive error </li></ul><ul><li>Normal or low AC/A ratio </li></ul><ul><li>Normal near point of accommodation </li></ul><ul><li>No reduction in angle with plus lenses </li></ul><ul><li>Normal sensory and motor fusion </li></ul><ul><li>Thought to be due to high proximal convergence or high tonic convergence </li></ul>
  29. 29. Distance Esotropia <ul><li>Rare </li></ul><ul><li>SOT for distance, SOP for near </li></ul><ul><li>No significant refractive error </li></ul><ul><li>VA normal and equal </li></ul><ul><li>Full ocular movements (differentiates 6 th nerve palsy or dysthyroid eye disease) </li></ul>
  30. 30. Cyclic Esotropia <ul><li>Esotropia occurring at regular intervals of time, BSV at others </li></ul><ul><li>Usual pattern = 24 hrs SOT/ 24 hrs BSV = “alternate day strabismus” </li></ul><ul><li>Onset 4-5 years or older </li></ul><ul><li>Most emmetropic with equal VAs </li></ul><ul><li>Diplopia rare </li></ul><ul><li>Gradually becomes constant - then surgery can be considered </li></ul><ul><li>Often associated with a psychogenic disturbance </li></ul>
  31. 31. Consecutive Esotropia <ul><li>Spontaneous – following XOT (rare – occurs with DVD) </li></ul><ul><li>Post-operative – following overcorrection of an XOT </li></ul>
  32. 32. Symptomatic (secondary) esotropia <ul><li>Following severe visual loss in childhood, due to muscle tonus </li></ul>
  33. 33. The management of non-refractive SOT is almost always surgical. <ul><li>Can try prism for distance SOT where angle < 10 ∆ (Use Fresnel lens initially – adaptation) </li></ul><ul><li>Correct the refractive error to remove any astenopia (independent of the deviation) </li></ul><ul><li>Any amblyopia must be treated. </li></ul>
  34. 34. Essential Infantile Esotropia <ul><li>Occurs before 6 months (usually 3-6 months) </li></ul><ul><li>Usually large angle (>40 ∆) </li></ul><ul><li>Same angle distance and near </li></ul><ul><li>Crossed alternating fixation </li></ul><ul><li>Less than half have ambyopia with EF (Dale, 1982) </li></ul><ul><li>May have latent nystagmus </li></ul><ul><li>Sometimes have DVD </li></ul><ul><li>Looks like a bilateral LR palsy (distinguish by “dolls head” movement) </li></ul>
  35. 35. Nystagmus Blocking (or compensation) Syndrome <ul><li>Convergent strabismus is adopted to lessen the nystagmoid movements which are reduced on convergence of the eyes </li></ul><ul><li>Pxs head usually turned away from side of fixing eye – produces greater convergence of this eye. </li></ul>
  36. 36. Accommodative Infantile Esotropia <ul><li>Rare </li></ul><ul><li>Most are hyperopic </li></ul><ul><li>Half have a high AC/A ratio </li></ul><ul><li>BV weak and unstable compared with later onset accommodative strabismus </li></ul><ul><li>Strabismic amblyopia </li></ul>
  37. 37. Sixth Nerve Palsy <ul><li>Rare in isolation, but can occur with neurological disorders eg hydrocephalus </li></ul><ul><li>Can be caused by trauma in forceps delivery NONE OF THESE CONDITIONS CAN BE TREATED BY REFRACTIVE OR ORTHOPTIC TREATMENT ALONE : SURGICAL TREATMENT SHOULD BE SOUGHT AS SOON AS POSSIBLE </li></ul>
  38. 38. Nature and Management of Comitant Divergent Strabismus
  39. 39. Divergence Excess <ul><li>Manifest for distance fixation only, usually intermittently but may be constant </li></ul><ul><li>Most apparent during inattention, ill health and fatigue, after alcohol and in bright light </li></ul><ul><li>Mostly females </li></ul><ul><li>Little refractive error </li></ul><ul><li>VA usually good and equal </li></ul><ul><li>Usually no symptoms as the sensory adaptations are good </li></ul><ul><li>Px may not have known about strabismus until told by others </li></ul><ul><li>AC/A is normal in true, but high in pseudo-divergence excess </li></ul>
  40. 40. Management <ul><li>Correction of myopia or anisometropia </li></ul><ul><li>Low degrees of hyperopia best left uncorrected </li></ul><ul><li>Most require referral for surgery </li></ul><ul><li>Where angle is <15∆ (rare – usually much larger) and BSV maintained most of the time, optical &/or orthoptic treatment may be of benefit – but usually only in the short term to delay surgery </li></ul>
  41. 41. Management <ul><li>Orthoptics : anti-suppression exercises (only if NRC) Exercise base out prism vergences Teach physiological diplopia (so Px knows when strabismic) </li></ul><ul><li>Optical:negative lenses can be successful in the short term, where accommodation is good </li></ul><ul><li>Prisms (full base in – then gradually reduce) – short term </li></ul><ul><li>Tinted spectacles – useful in countries with high light intensity – again only short-term- high illumination has a dissociating effect in exodeviations – can cause suppression or closing of one eye PROBABLY BEST TO REFER FOR SURGERY FROM OUTSET </li></ul>
  42. 42. Near Exophoria (Convergence Insufficiency) <ul><li>Most commonly occurs in the mid-teens when reduced convergence &/or increased myopia break down the BV, can be in adults </li></ul><ul><li>Rarely occurs at around 5-7 years old with an accommodative element – usually low AC/A </li></ul><ul><li>Typically XOP at distance XOT at near </li></ul><ul><li>Pxs present with symptoms (diplopia, astenopia) </li></ul><ul><li>Usually equal VAs, poor or no convergence, NRC and normal sensory fusion with poor positive fusional amplitude </li></ul><ul><li>Often myopic </li></ul>
  43. 43. Management <ul><li>If strabismus is constantly manifest for near and angle >25∆ - refer </li></ul><ul><li>For smaller angles and only occasionally manifest: </li></ul><ul><ul><li>Correct any myopia (this may be enough to make deviation latent) </li></ul></ul><ul><ul><li>Orthoptics – exercise base out prism vergences (often successful) </li></ul></ul><ul><ul><li>Prisms – base In just sufficient to enable BSV for near (Usually tolerated for distance) </li></ul></ul><ul><ul><li>gradually reduce the strength of the prism and combine with orthoptics </li></ul></ul><ul><ul><li>Occasionally try negative adds </li></ul></ul><ul><ul><li>If no improvement – refer for surgery. </li></ul></ul>
  44. 44. Constant (Basic) Exotropia <ul><li>Constant divergent strabismus, equal angles distance and near </li></ul><ul><li>Onset in early childhood: no symptoms, no sensory fusion </li></ul><ul><li>Closure of one eye in bright light </li></ul><ul><li>Often alternating, with equal VAs; homonymous fixation </li></ul>
  45. 45. Management <ul><li>Surgical correction for cosmetic (or occasionally functional) result </li></ul><ul><li>Occasionally in children <7 years old – try –ve additions to eliminate strabismus on the CT in conjunction with exercises to establish BSV. </li></ul><ul><li>Gradually try to phase out the –ve add over several years. </li></ul><ul><li>If a divergent strabismus has a vertical component – orthoptics not successful </li></ul>
  46. 46. Consectutive Exotropia <ul><li>Spontaneous – usually occurs following early onset partially accommodative esotropia with a high degree of hyperopia. </li></ul><ul><li>Develops as the amplitude of accommodation decreases, or precipitated by the late correction of hyperopia </li></ul><ul><li>Post-operatively – usually several years after surgical correction of accommodative SOT – especially if hyperopic correction is now prescribed </li></ul>
  47. 47. Management <ul><li>Partial correction of hyperopia + Base out prism </li></ul><ul><li>vergence exercises sometimes helps </li></ul><ul><li>Remedial surgery </li></ul>
  48. 48. Symptomatic (Secondary) Exotropia <ul><li>Due to severe loss of vision in one eye in adult life </li></ul><ul><li>Management = Cosmetic surgery </li></ul>
  49. 49. Onset of Exotropia before 1 year old <ul><li>Usually symptomatic (or secondary) due to visual loss from birth </li></ul><ul><li>Rarely congenital exotropia, often with nystagmus and DVD </li></ul><ul><li>Management </li></ul><ul><li>No optometric treatment - refer </li></ul>
  50. 50. Vertical Heterophoria Hyperphoria <ul><li>a potential deviation of one eye upwards which becomes an actual deviation when the two eyes are dissociated and recovers when the dissociating factors are removed </li></ul><ul><li>15-30% patients have a measureable hyperphoria (not necessarily decompensated). </li></ul>
  51. 51. Two types <ul><li>Secondary </li></ul><ul><li>Primary </li></ul>
  52. 52. Secondary hyperphoria <ul><li>Horizontal heterophoria </li></ul><ul><li>Incomitant deviations </li></ul><ul><li>Tilted spectacles </li></ul>
  53. 53. Primary/True hyperphoria – <ul><li>seldom >3  </li></ul><ul><li>is considered largely due to slight anatomical misalignment of the eyes or orbits or muscle insertions for which there is physiological compensation </li></ul>
  54. 54. Investigation
  55. 55. Symptoms <ul><li>Marked with low degrees </li></ul><ul><li>Frontal HA’s; pain, soreness of lid margins </li></ul><ul><li>Head tilt alleviates symptoms </li></ul><ul><li>Prefers monocular vision </li></ul><ul><li>Motility - Evaluate carefully to ensure there is no paresis </li></ul><ul><li>Refraction – very important to assess binocular balancing, and check if both images are aligned (Mallett units are useful for this or infinity balance techniques). </li></ul>
  56. 56. Management <ul><li>Remove cause of decompensation ie pay attention to working conditions, any stress or ill health of the patient </li></ul><ul><li>RE: Rx may alleviate symptoms anisometropia – take care to prevent vertical problems. </li></ul><ul><li>Orthoptics: if associated with horizontal phoria, development of horizontal fusional reserves may result in the vertical phoria becoming compensated. </li></ul><ul><li>Prisms: perhaps best method of treatment especially for primary vertical hyperphoria. The minimum amount of prism should be prescribed and the prism should be divided between the two eyes or the maximum prism is placed before the non-dominant eye. </li></ul><ul><li>Surgery: May be necessary in high hyperphoria or Incomitancy </li></ul><ul><li>Truly comitant hyperdeviations are rare. </li></ul>
  57. 57. Dissociated Vertical Deviation (alternating sursumduction) <ul><li>Can be mistaken as a hyperphoria </li></ul><ul><li>During CT the covered eye deviates slowly up to  25  </li></ul><ul><li>Eye tends to extort on cover </li></ul><ul><li>When cover is removed eye returns to fixation position </li></ul><ul><li>Movement may not be equal between the eyes </li></ul><ul><li>Can be accompanying cyclorotation </li></ul><ul><li>Latent nystagmus is common associated finding </li></ul><ul><li>Obscure </li></ul><ul><li>No symptoms- no treatment </li></ul><ul><li>If co-exists with another deviation, treatment appropriate to the other deviation is given if symptoms exist. </li></ul>
  58. 58. Dissociated Vertical Deviation (alternating sursumduction) Stidwell, 1997
  59. 59. A and V Patterns <ul><li>These deviations show variations in horizontal magnitude as the fixation point moves up and down. </li></ul><ul><li>may be associated with convergence or divergence and occur in both heterotropia and heterophoria. </li></ul>
  60. 60. Convergence <ul><li>A pattern Increased convergence on elevation Decreased convergence on depression </li></ul><ul><li>V pattern increased convergence on depression decreased convergence on elevation </li></ul>
  61. 61. Divergence <ul><li>A pattern increased divergence on depression decreased divergence on elevation </li></ul><ul><li>V Pattern -increased divergence on elevation decreased divergence on depression </li></ul>
  62. 62. The aetiology of A and V patterns <ul><li>is not agreed and may vary between individuals although over- and under-action of the oblique muscles appears to be the most likely cause. </li></ul><ul><li>It is thought that bilateral inferior oblique overaction produces a V pattern in both eso and exo deviations; and bilateral superior oblique overactions produces the A pattern. </li></ul>
  63. 63. Cyclodeviations <ul><li>Incidence not known </li></ul><ul><li>Usually caused by an imbalance between the muscle pair affecting intorsion (SO and SR) and the muscle pair inducing extorsion (IO and IR ). </li></ul><ul><li>Doubtful if cyclophoria exists as a primary cyclophoria although authorities give methods for its detection. </li></ul>
  64. 64. Pseudostrabismus <ul><li>Epicanthus in infants can be more or less pronounced. </li></ul><ul><li>Epicanthus can obscure the inner canthus giving rise to the appearance of esotropia when none is present. </li></ul><ul><li>In time epicanthal fold usually disappears with the development of the bridge of the nose </li></ul><ul><li>Other examples of pseudostrabismus include </li></ul><ul><ul><li>facial asymmetry </li></ul></ul><ul><ul><li>failure of the optical (centres of the cornea and lens) and visual axis (fovea to fixation point) to coincide </li></ul></ul>